| Customization: | Available |
|---|---|
| CAS No.: | 3 Years |
| Formula: | Culture Medium |
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023062 Deoxycholate Hydrogen Sulfide Lactose Agar(DHL)
Usages:
For selective separation of enteric pathogens particularly for Salmonella and Shigella.
Peptone, beef extract powder provides carbon, nitrogen, vitamins and minerals; lactose, sucrose as fermentable sugars; sodium deoxycholate and sodium citrate to inhibit gram-positive bacteria and most of the coliform and Proteus, but it does not affect the growth of Salmonella; sodium thiosulfate and ferric ammonium citrate for the detection of hydrogen sulfide, so that the center of the colony was black; neutral red as pH indicator, colonies of fermentable sugars acid production was red, does not ferment sugar colonies colorless; agar medium as coagulant.
Formulation (per liter):
Peptone 20.0g
Lactose 10.0g
Beef extract powder 3.0g
Sucrose 10.0g
Sodium deoxycholate 1.0g
Sodium thiosulfate 2.3g
Sodium citrate 1.0g
Ferric ammonium citrate 1.0g
Neutral Red 0.03g
Agar 16.0g
Final pH 7.2 ± 0.1
Storage: Keep container tightly closed, store in a cool, dry place, away from bright light. Storage period of 3 years.
Specifications: 250g
Packing material: Packed in plastic bottles with plastic film wrapped
Capacity:250g/bottle, 20 bottle/ carton Carton
1.Offering Free Sample for Testing .
2.R & D team to provide technical support.
3.Provide packaging, labeling OEM customization.
Q1:
Sometimes color of dehydrated culture media between batches have subtle differences,would this affect test results?
A1:The source and storage conditions of raw material is different ,so there may be a slight difference in color, which is a normal phenomenon. Products from our company have to undergo a rigorous inspection and sensory biology verification before sale, to ensure that all the indicators characteristics of the product is under enterprise standard to the extent permitted, not affect the test results.
Q2:
After pouring the liquid medium on the plate , medium seems hard to clot or coagulation time is longer, is it some problem with product quality?
A2: The reason may be:
The required hydration in the preparation process have not been done completely .That is to say distilled water is not boil sufficiently to dissolve agar. Because agar proportion, easily settle in the bottom of the bottle, if not fully shaken after high-temperature sterilization, it will lead to uneven upper agar culture gene content and difficult to set.
Q3:
Why some colonies of E. coli chromogenic medium color not shown above, but also confirmed through biochemical tests for E. coli (false negative)?
A3: E. CHROMOGENIC medium is based on the principle of specific enzyme of E. coli and design, 94% of E. coli have β- glucuronidase enzyme, with the chromogenic enzyme substrate medium role in the formation of blue-green colonies. And about 4% of the E. coli does not have β- glucuronidase enzymes, including concern O157: H7 Escherichia coli. Therefore, these E. coli can not be displayed on the color characteristic of E. coli chromogenic medium,it is possible of false-negative on the chromogenic medium. However, the traditional medium of the same can not avoid the problem of false negatives, such as: no gas or slow ferment lactose intolerance may also strain 44.5 false negatives in the conventional medium. For this small part of the E. coli can be detected using other methods.
Q4:
During anaerobic or micro-aerobic culture, is it necessary to remove gas bag from package? How to use oxygen indicator?
A4: During anaerobic or micro-aerobic culture, using method of gassing agent should be done according to the manufacturer's instructions. Remove the paper bag from the plastic packaging, but do not cut the paper bag. Torn the outer packaging of oxygen indicator then it can be used.
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